Title :
Work Function Tuning and Material Characteristics of Lanthanide-Incorporated Metal Nitride Gate Electrodes for NMOS Device Applications
Author :
Ren, Chi ; Chan, Daniel Siu Hung ; Li, Ming-Fu ; Loh, Wei-Yip ; Balakumar, S. ; Tung, Chih Hang ; Balasubramanian, N. ; Kwong, Dim-Lee
Author_Institution :
Dept. of Electr. & Comput. Eng., Nat. Univ. of Singapore
Abstract :
A versatile method to tune the work function PhiM of metal nitride (MNx) metal gates by incorporating lanthanide elements for the applications in NMOS devices is demonstrated. By incorporating lanthanide elements such as terbium (Tb), erbium (Er), or ytterbium (Yb) into MNx metal gates such as TaN and HfN, the work function of these MNx can be tuned continuously down to 4.2-4.3 eV even after rapid thermal annealing up to 1000 degC, owing to the very low PhiM values of lanthanide elements. Material and electrical properties of lanthanide-MNx are investigated, and the results indicate that N concentration is an important parameter for the resistivity, work function, and thermal stability of lanthanide-MNx metal gates. Therefore, it needs to be carefully optimized in the process. In addition, transistor characteristics with Ta0.9Tb0.1Ny on SiO2 are also demonstrated, and several issues regarding the process integration of these novel materials are discussed
Keywords :
MOSFET; hafnium compounds; rapid thermal annealing; rare earth metals; tantalum compounds; work function; 1000 C; 4.2 to 4.3 eV; HfN; SiO2; Ta0.9Tb0.1N; TaN; lanthanide elements; lanthanide-incorporated metal nitride gate electrodes; nMOS device; thermal annealing; work function tuning; CMOS process; Dielectric materials; Electrodes; Erbium; Inorganic materials; MOS devices; MOSFETs; Rapid thermal annealing; Silicon; Thermal stability; Lanthanide; NMOS; metal gate electrode; metal nitride (; work function;
Journal_Title :
Electron Devices, IEEE Transactions on
DOI :
10.1109/TED.2006.878017
